Method and compositions

ABSTRACT

The invention relates to a method for inhibiting the growth of microorganisms in a latex, especially a sterically stabilised or cationic stabilised latex and to a composition for use in the method comprising a polymeric biguanide and an isothiazolinone of the Formula (1).  
                 
 
     wherein:  
     R is H, alkyl, cycloalkyl or aralkyl; and  
     Y and Z each independently are H, halogen or C 1-4 -alkyl or Y and Z together with the carbon atoms to which they are attached form an optionally substituted 5 or 6 membered ring.

METHOD AND COMPOSITIONS

[0001] The present invention relates to a method for inhibiting thegrowth of micro-organisms in a latex, especially a sterically stabilisedor cationic stabilised latex and to compositions for use in the method.

[0002] Latices are a colloidal dispersion of a polymeric substance in aliquid medium which is usually aqueous and are used widely in manyindustrial applications such as paints, adhesives and sealants. However,latices are prone to attack by various micro-organisms which can resultin an number of undesirable side effects including discolouration of thelatex, destabilisation of the latex, loss of latex viscosity, theproduction of mal odours, the production of corrosive by-productsresulting from the microbial metabolism and the generation of gasesduring storage. To minimise these problems anti-microbial agents areadded to the latex to inhibit the growth of micro-organsims.

[0003] 1,2-benzisothiazolin-3-one is used as a preservative in latices,particularly for the preservation of paints. This compound iscommercially available from Avecia Limited as Proxel™ .

[0004] Various isothiazolinone derivatives are also used in thepreservation of latices, for example2-methyl-4,5-trimethylene-4-isothiazolin-3-one and a blend of5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one(commercially available as Kathon™ from Rohm and Haas). Biocides arealso added to latices to provide protection to the end use of the latex.For example, 2-n-octyl-4-isothiazolin-3-one (commercially available asSkane™ from Rohm & Haas) is used to inhibit the growth of mildew onpaint films.

[0005] However, certain micro-organisms commonly found in latices,especially pseudomonad species are more tolerant of isothiazolinones andcan therefore be more difficult to control.

[0006] We have surprisingly found that a combination of certainanti-microbial compounds provide improved efficacy when used to inhibitthe growth of micro-organisms in a latex.

[0007] According to a first aspect of the present invention there isprovided a method for inhibiting the growth of micro-organisms in alatex comprising adding to the latex:

[0008] (a) a polymeric biguanide; and

[0009] (b) an isothiazolinone of the Formula (1) or a salt or complexthereof:

[0010] wherein:

[0011] R is H, alkyl, cycloalkyl or aralkyl; and

[0012] Y and Z each independently are H, halogen, C₁₋₄-alkyl or Y and Ztogether with the carbon atoms to which they are attached form anoptionally substituted 5 or 6 membered ring.

[0013] Isothiazolinone

[0014] When R is alkyl it may be linear or branched but is preferablylinear. Preferred alkyl groups include C₁₋₈-alkyl, more preferablyC₁₋₄-alkyl. Examples of preferred alkyl groups include for examplemethyl, ethyl, n-propyl, isopropyl, n-pentyl, n-butyl, isobutyl,tert-butyl and n-octyl.

[0015] When R is cycloalkyl, it is preferably cyclopropyl, cyclopentyl,or cyclohexyl.

[0016] When R is aralkyl, it preferably contains from 1 to 6, mostpreferably 1 or 2 carbon atoms in the alkylene group attaching the arylgroup to the isothiazolinone ring. Preferred aralkyl groups includebenzyl, 2-naphthylethyl and especially 2-phenylethyl.

[0017] When Y or Z is halogen it is preferably iodine, bromine andespecially chlorine.

[0018] When Y and Z together with the carbon atoms to which they areattached form an optionally substituted 5 or 6 membered ring it ispreferably an optionally substituted aryl (especially an optionallysubstituted benzene ring), an optionally substituted cyclopentene or anoptionally substituted cyclohexene ring. Preferred optional substituentson the 5- or 6-membered ring are selected from hydroxy, halogen(especially chlorine), C₁₋₄-alkyl and C₁₋₄-alkoxy. It is preferredhowever that the ring is unsubstituted.

[0019] When Y and Z are H, halogen or C₁₋₄-alkyl, it is preferred that Ris C₁₋₈-alkyl, C₃₋₅-cycloalkyl or aralkyl, more preferably C₁₋₈-alkyland especially C₁₋₄-alkyl.

[0020] In an embodiment of the invention when R is n-octyl it ispreferred that Y and Z are either both chlorine or both hydrogen. Suchisothiazolinones are disclosed in U.S. Pat. No. 4,105,431.

[0021] Examples of suitable isothiazolinones include5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one,4,5-dichloro-2-methylisothiazolin-3-one, 2-n-octylisothiazolin-3-one,1,2-benzisothiazolin-3-one, 4,5-trimethylene-4-isothiazolin-3-one and2-methyl-4,5-trimethylene-4-isothiazolin-3-one,2-n-butyl-1,2-benzisothiazolin-3-one and mixtures comprising two or moreof the foregoing compounds.

[0022] In a preferred embodiment of the present invention theisothiazolinone of Formula (1) is a benzisothiazolinone of the Formula(2) or a salt or complex thereof:

[0023] wherein:

[0024] R¹ is hydroxy, halogen (especially chlorine), C₁₋₄-alkyl orC₁₋₄-alkoxy;

[0025] R is as hereinbefore defined; and

[0026] n is from 0to 4.

[0027] R¹, when present, is preferably located in one or both of the 5and 6 positions of the phenyl ring of the benzisothiazolinone. However,it is particularly preferred that n is zero.

[0028] Preferred benzisothiazolinones of the Formula (2) are those inwhich R is H or C₁₋₅-alkyl, more preferably H or C₃₋₅-alkyl. Examples ofcompounds of the Formula (2) include, for example1,2-benzisothiazolin-3-one, N-n-butyl-, N-methyl-, N-ethyl-,N-n-propyl-, N-isopropyl-, N-n-pentyl-, N-cyclopropyl-, N-isobutyl-, andN-tert-butyl-1,2-benzisothiazolin-3-one. It is especially preferred thatthe benzisothiazolinone of Formula (2) is 1,2-benzisothiazolin-3-one.

[0029] When R is H in Formula (1) or Formula (2) the isothiazolinone maybe used in the form of a salt or complex thereof. The salt or complexmay be with any suitable cation such as an amine (including analkanolamine) or a metal. Preferred salts are those with a monovalentmetal especially an alkali metal salt such as lithium, sodium orpotassium. Most preferably, the alkali metal salt is a sodium salt.

[0030] Polymeric Biguanide

[0031] Preferably the polymeric biguanide comprises at least twobiguanide units of Formula (3):

[0032] linked by a bridging group which contains at least one methylenegroup. The bridging group preferably includes a polymethylene chain,optionally incorporating or substituted by one or more hetero atoms suchas oxygen, sulphur or nitrogen. The bridging group may include one ormore cyclic moieties which may be saturated or unsaturated. Preferably,the bridging group is such that there are at least three, and especiallyat least four, carbon atoms directly interposed between two adjacentbiguanide units of Formula (3). Preferably, there are not greater thanten and especially not greater than eight carbon atoms interposedbetween two adjacent biguanide units of Formula (3).

[0033] The polymeric biguanide may be terminated by any suitable group,such as a hydrocarbyl, substituted hydrocarbyl or an amine group or acyanoguanidine group of the formula:

[0034] When the terminating group is hydrocarbyl, it is preferablyalkyl, cycloalkyl, aryl or aralkyl. Preferred alkyl, cycloalkyl, aryl oraralkyl groups are as defined for R in Formula (1). Preferred arylgroups include phenyl groups. When the terminating group is substitutedhydrocarbyl, the substituent may be any substituent that does notexhibit undesirable adverse effects on the microbiological properties ofthe polymeric biguanide. Examples of such substituents are aryloxy,alkoxy, acyl, acyloxy, halogen and nitrile.

[0035] When the polymeric biguanide contains two biguanide groups ofFormula (3) the biguanide is a bisbiguanide. The two biguanide groupsare preferably linked through a polymethylene group, especially ahexamethylene group.

[0036] The terminating groups in such bisbiguanides are preferablyC₁₋₁₀-alkyl which may be linear or branched and optionally substitutedaryl, especially optionally substituted phenyl. Examples of suchterminating groups are 2-ethylhexyl and 4-chlorophenyl. Specificexamples of such bisbiguanides are compounds represented by Formula (4)and (5) in the free base form:

[0037] The polymeric biguanide preferably contains more than twobiguanide units of Formula (3) and is preferably a linear polymericbiguanide which has a recurring polymeric chain represented by Formula(6) or a salt thereof:

[0038] wherein X and Y represent bridging groups which may be the sameor different and in which together the total of the number of carbonatoms directly interposed between the pairs of nitrogen atoms linked byX plus the number of carbon atoms directly interposed between the pairsof nitrogen atoms linked by Y is more than 9 and less than 17.

[0039] The bridging groups X and Y preferably consists of polymethylenechains, optionally interrupted by hetero atoms, for example, oxygen,sulphur or nitrogen. X and Y may also incorporate moieties which may besaturated or unsaturated, in which case the number of carbon atomsdirectly interposed between the pairs of nitrogen atoms linked by X andY is taken as including that segment of the cyclic group, or groups,which is the shortest. Thus, the number of carbon atoms directlyinterposed between the nitrogen atoms in the group

[0040] is 4 and not 8.

[0041] The linear polymeric biguanides having a recurring polymer unitof Formula (6) are typically obtained as mixtures of polymers in whichthe polymer chains are of different lengths. Preferably, the number ofindividual biguanide units of formulae:

[0042] is, together, from 3 to about 80.

[0043] The preferred linear polymeric biguanide is a mixture of polymerchains in which X and Y are identical and the individual polymer chains,excluding the terminating groups, are of the Formula (7) or a saltthereof:

[0044] wherein n is from 4 to 40 and especially from 4 to 15. It isespecially preferred that the average value of n is about 12.Preferably, the average molecular weight of the polymer in the free baseform is from 1100 to 3300.

[0045] The linear polymeric biguanides may be prepared by the reactionof a bisdicyandiamide having the formula:

[0046] with a diamine H₂N—Y—NH₂, wherein X and Y have the meaningsdefined above, or, by reaction between a diamine salt or dicyanimidehaving the formula:

[0047] with a diamine H₂N—Y—NH₂ wherein X and Y have the meaningsdefined above. These methods of preparation are described in UKspecifications numbers 702,268 and 1,152,243 respectively, and any ofthe polymeric biguanides described therein may be used in the presentinvention.

[0048] As noted hereinbefore, the polymer chains of the linear polymericbiguanides may be terminated either by an amino group or by acyanoguanidine group:

[0049] This cyanoguanidine group can hydrolyse during preparation of thelinear polymeric biguanide yielding a guanidine end group. Theterminating groups may be the same or different on each polymer chain.

[0050] A small proportion of a primary amine R—NH₂, where R representsan alkyl group containing from 1 to 18 carbon atoms, may be includedwith the diamine H₂N—Y—NH₂ in the preparation of polymeric biguanides asdescribed above. The primary amine acts as a chain-terminating agent andconsequently one or both ends of the polymeric biguanide polymer chainsmay be terminated by an —NHR group. These —NHR chain-terminatedpolymeric biguanides may also be used.

[0051] The polymeric biguanides readily form salts with both inorganicand organic acids. Preferred salts of the polymeric biguanide arewater-soluble. When the polymeric biguanide is represented by a compoundof Formula (4) in the free base form, a preferred water soluble salt isthe digluconate. When the polymeric biguanide is represented by acompound of Formula (5) in the free base form, a preferred water solublesalt is the diacetate. When the polymeric biguanide is a mixture oflinear polymers represented by Formula (7) in the free base form, thepreferred salt is the hydrochloride.

[0052] It is especially preferred that the polymeric biguanide is amixture of linear polymers, the individual polymer chains of which,excluding the terminating groups, are represented by Formula (7) in thehydrochloride salt form. This is commercially available from Avecia Ltd.under the trademark VANTOCIL™.

[0053] Latex

[0054] The present method is suitable for protecting a wide range oflatices. The latex may be a natural latex, for example as produced byrubber trees, an artificial latex, prepared by dispersing polymerparticles in a liquid medium or more preferably, a synthetic latexprepared by emulsion polymerisation of one or more monomers.

[0055] The polymer particles in the latex are usually stabilised in theliquid medium using ionic or steric forces to inhibit theflocculation/coagulation of the polymer particles in the liquid medium.When the latex is stabilised using ionic stabilisation the polymerparticles are stabilised primarily by cationic or anionic groupsassociated with the surface of the polymer particles. The ionic groupsmay be present as an ionic surfactant/dispersant present in the liquidmedium of the latex or as an ionic group which is an integral part ofthe polymer. Such ionic groups may be introduced into the polymer byusing cationic or anionic monomers during the emulsion polymerisationprocess used to prepare the latex.

[0056] When the latex is stabilised using steric stabilisation thepolymer particles are stabilised principally using steric hindranceprovided by non-ionic surfactants/dispersants or water-soluble colloids.

[0057] When the latex is an anionic stabilised latex it is preferablystabilised using an anionic surfactant, or by anionic groups which formpart of the polymer particle in the latex.

[0058] Suitable anionic surfactants include alkylarylsulfonates (forexample calcium dodecylbenzenesulfonate), alkylsulfates (for examplesodium dodecylsulfate), sulfosuccinates (for example sodiumdioctylsulfosuccinate), alkylethersulfates, alkylarylethersulfates,alkylether carboxylates, alkylarylethercarboxylates, lignin sulfonatesor phosphate esters.

[0059] When the latex is stabilised by anionic groups present in thepolymer of the latex the groups are preferably introduced bypolymerising or more preferably co-polymerising anionic monomers duringthe emulsion polymerisation process used in the preparation of thelatex. Suitable anionic monomers which may be used in the preparation ofthe latex include those which carry one or more sulpho or, morepreferably carboxy groups or salts thereof. For example, an unsaturatedmono or dicarboxylic acid. Suitable unsaturated mono carboxylic acidsinclude acrylic acid or methacrylic acid. Suitable unsaturateddicarboxylic acids include itaconic acid, fumaric acid or maleic acid.

[0060] However, it is preferred that the latex is a cationic orsterically stabilised latex, because we have found that the presence ofsome anionic surfactants can result in the formation of undesirableprecipitates when the isothiazolinone and polymeric biguanide are addedto the latex. Accordingly it is preferred that the latex issubstantially free from anionic compounds, especially anionicsurfactants. Preferably the latex contains less than 5%, more preferablyless than 1% and especially less than 0.05% by weight of anioniccompounds, for example anionic surfactants such as alkyl sulphonate oralkyl carboxylates.

[0061] When the latex is a cationic stabilised latex it is preferablystabilised using a cationic surfactant, or by cationic groups which formpart of the polymer particle in the latex.

[0062] Suitable cationic surfactants include aliphatic, mono-, di- andpolyamines derived from fatty and rosin acids, especially those with oneor more tertiary or quaternary ammonium groups. Preferably the fatty androsin acids from which the surfactants are derived contain one or moreC₁₀₋₂₄-alkyl or alkenyl groups more preferably C₁₂₋₂₄-alkyl or alkenylgroups more preferably a C₁₆₋₁₈-alkyl or alkenyl group. Suitable aminesurfactants include diamines of the formula R²NH(CH₂)_(m)NH₂ wherein mis 2 or 3 and R² is a mixed alkyl or alkenyl group derived from coconut,tallow or soyabean oil; alkylamine ethoxylates such as aliphatic amineethoxylates, and fatty alkyl-1,3-propanediamine ethoxylates;ethylenediamine alkoxylates; 2-alkyl imidazolines and ethoxylatedderivatives thereof; and alkoxylated allkanolamides. Suitablesurfactants containing quaternary ammonium group(s) include for exampledi(hydrogenated tallow alkyl)-dimethyl quaternary ammonium chloridessuch as Arquad™. 2HT-75 (Akzo Chemicals Inc., Chicago, Ill.); tallowalkyl benzyl dimethyl quaternary ammonium chloride such as Kemamine™BQ-9742C (Witco Chemical Corp., Memphis, Tenn.); hydrogenated tallowalkyl benzyl dimethyl quaternary ammonium chloride such as Kemamine™Q-9702C (Witco Chemical Corp.); methyl bis(soya alkyl amidoethyl)2-hydroxyethyl quaternary ammonium methyl sulfate such as Accosoft™ 750(Stepan Co., Northfield, Ill.); methyl bis(tallow alkyl amidoethyl)2-hydroxyethyl quaternary ammonium methyl sulfate such as Accosoft™ 501(Stepan Co.); fatty-alkyl trimethlammonium salts, for exampletallow-alkyl trimethlammonium salts; fatty-alkylpyridinium salts forexample cetylpyridinium chloride; and quaternary ammonium esters.

[0063] When the latex is stabilised by cationic groups present in thepolymer of the latex the groups are preferably introduced bypolymerising or more preferably co-polymerising cationic monomers duringthe emulsion polymerisation process used in the preparation of thelatex. Preferred cationic monomers are those which carry one or morecationic group(s), especially vinyl, acrylate and (alkyl) acrylate(especially (meth)acrylate, (ethyl)acrylate and (propyl)acrylate)monomers which carry a cationic group.

[0064] Suitable cationic groups carried by the monomers include amines,preferably secondary or more preferably tertiary amines; nitrogencontaining heterocyclic groups, for example pyridyl or pyrrolidonegroups; and quaternary ammonium groups.

[0065] Examples of preferred cationic acrylate and (alkyl)acrylatemonomers include 2-dimethylaminoethyl) acrylate, 2-(dimethylaminoethyl)(meth)acrylate, 2-(dimethylaminoethyl) (ethyl)acrylate or2-(dimethylaminoethyl) (propyl)acrylate and quaternary ammonium saltsthereof, especially the dimethyl sulphate quaternary ammonium salt.Examples of preferred vinyl monomers carrying a cationic group includevinyl pyridine or vinyl pyrrolidone and salts thereof.

[0066] When the latex is sterically stabilised it is preferablystabilised using a non-ionic surfactant or dispersant or a water-solublecolloid. A wide range of non-ionic surfactants are suitable forstabilising the latex, the selection of which will depend upon thepolymer in the latex and the end use of the latex. Suitable non-ionicsurfactants include polyoxyethylene surfactants; alcohol ethoxylates;alkylphenolethoxylates; carboxylic acid esters, preferably thoseobtained by reaction of a fatty acid and a polyol; glycerol esters offatty acids; polyoxyethylene esters obtainable from the reaction of afatty acid with a polyethylene glycol; carboxylic amides especiallythose obtainable by the condensation of fatty acids with ahydroxyalkylamine or a diethanolamine; ethoxylated fatty acid amides;polyalkyleneoxide block copolymers, especiallypoly(oxyethylene-co-oxypropylene) surfactants.

[0067] Suitable water-soluble colloids which may be used to stabilisethe latex are water-soluble long chain polymers, for example apoly(vinylacetate) and partially hydrolysed derivatives thereof;polyvinylalcohols; starches, hydroxethylcellulose and glycol etherderivatives thereof; and hydroxymethyl cellulose and glycol etherderivatives thereof.

[0068] It is especially preferred that the latex is stabilised with apartially hydrolysed poly(vinylacetate) or a poly(vinylalcohol).Suitable examples are those available from Hoechst Aktingesellschaftunder the trade name Mowiol™ 8-88 and Mowiol™ 18-88 but are not limitedthereto.

[0069] As hereinbefore mentioned the method according to the presentinvention may be used to protect a wide range of latices. The polymerparticles present in the latex will be dependent upon the endapplication of the latex. Suitable latices include, but are not limitedto those obtainable by the polymerisation or emulsion polymerisation ofone or more acrylates and (alkyl)acrylates (especially alkylacrylatesand alkyl(meth)acrylates); optionally substituted styrenes;methacrylamides; allyl compounds; vinyl ethers; vinyl ketones; vinylesters; vinyl halides; olefins; unsaturated nitriles and mixturescomprising two or more of the foregoing.

[0070] Examples of suitable alkyl acrylates and alkyl(meth)acrylatesinclude methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropylacrylate, n-butyl acrylate, isobutyl, sec-butyl acrylate, amyl acrylate,hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, tert-octylacrylate, 2-phenoxyethyl acrylate, di- and tripropylene glycoldiacrylate, 2-chloroethyl acrylate, 2-bromoethyl acrylate, 4-chlorobutylacrylate, cyanoethyl acrylate, 2-acetoxyethyl acrylate,dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate,2-clorocyclohexyl acrylate, cyclohexyl acylate, furfuryl acrylate,tetrahydrofurfuryl acrylate, hydroxyethyl(meth)acrylate,hydroxypropyl(meth) acrylate, 5-hydroxypentyl acrylate,2,2-dimethyl-3-hydoxypropyl acrylate, 2-methoxyethyl acrylate,3-methoxybutyl acrylate, 2-ethoxyethyl acrylate, 2-iso-propoxyethylacrylate, 2-butyoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate,2-(2-butoxyethoxy)ethyl acrylate, 1-bromo-2-methoxyethyl acrylate,1,1-dichloro-2-ethoxyethyl acrylate, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, sec-butyl methacrylate, amylmethacrylate, hexyl methacrylate, cyclohexyl methacrylate,benzylmethacrylate, chlorobenzyl methacrylate, octyl methacrylate,N-ethyl-N-phenylaminoethyl methacrylate, 2-(3-phenylpropyloxy)ethylmethacrylate, dimethylaminophenoxyethyl methacrylate and furfurylmethacrylate.

[0071] Suitable optionally substituted styrenes include styrene, divinylbenzene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene,diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene,cyclohexylstyrene, decylstyrene, chloromethylstyrene,trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene,methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene,chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene,pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene,trifluorostyrene and 2-bromo-4-trifluoromethylstyrene.

[0072] Suitable methacrylamides include those containing less than 12carbon atoms. Examples include methylmethacrylamide,tert-butylmethacrylamide, tert-octylmethacrylamide,benzylmethacrylamide, cyclohexylmethacrylamide, phenylmethacrylamide,dimethylmethacrylamide, dipropylmethacrylamide,hydroxyethyl-N-methylmethacrylamide, N-methylphenylmethacrylamide,N-ethyl-N-phenylmethacryiamide and methacrylhydrazine.

[0073] Suitable allyl compounds include allyl acetate, allyl caproate,allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allylbenzoate, allyl acetoacetate, allyl lactate, allyloxyethanol, allylbutyl ether and allyl phenyl ether.

[0074] Suitable vinyl ethers include those containing less than 20carbon atoms. Examples include methyl vinyl ether, butyl vinyl ether,hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexylvinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether,chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether,2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether anddimethylaminoethyl vinyl ether.

[0075] Suitable vinyl ketones include those containing less than 12carbon atoms. Examples include methyl vinyl ketone, phenyl vinyl ketoneand methoxyethyl vinyl ketone.

[0076] Suitable vinyl esters include vinylacetate.

[0077] Suitable vinyl halides include vinyl chloride, vinylidenechloride and chlorotrifluoro ethylene.

[0078] Suitable olefins include unsaturated hydrocarbons having lessthan 20 carbon atoms. Examples include dicyclopentadiene, propylene,1-butene, 1-pentene, 1-hexene, 4-methyl-1 -pentene, 1-heptene, 1-octene,1-decene, 5-methyl-1-nonene, 5,5-dimethyl-1-octene, 4-methyl-1-hexene,4,4-dimethyl-1-pentene, 5-methyl-1-hexene, 4-methyl-1-heptene,5-methyl-1-heptene, 4,4-dimethyl-1-hexene, 5,5,6-trimethyl-1-heptene,1-dodecene and 1-octadecene and especially ethylene.

[0079] Suitable unsaturated nitriles include acrylonitrile andmethacrylonitrile.

[0080] Further components may be added to the monomer(s) during thepreparation of the latex to modify the properties of the polymerparticles, for example plasticisers and stabilizers. The plasticiser orstabiliser may be any of those commonly used in the latices fabricationindustry and is preferably a liquid. Examples of suitable plasticisersor stabilisers are esters of aromatic and aliphatic mono- anddi-carboxylic acids and linear or branched alcohols especiallyC₈₋₁₀-alcohols; epoxidised fatty acid esters and epoxidised vegetableoils. Specific examples of plasticisers are di-hexyl-, di-octyl-,di-nonyl, di-isodecyl-, and di-(2-ethylhexyl)- adipates, sebacates,trimellitates and phthalates; epoxidised octyl stearate, epoxidised soyabean oil and phosphate esters of formula O═P(OR³)₃ wherein R³ ishydrocarbyl, particularly phenyl and especially C₁₋₄-alkyl and lowmolecular weight oligo- and poly-esters such as those obtainable byreacting 1,3-butanediol with adipic acid.

[0081] The pH of the latex is preferably from 3 to 10.

[0082] The present method is particularly effective for inhibiting thegrowth of micro-organisms in latices used in paints, adhesives andsealants. Examples of such latices include those obtainable by thepolymerisation or emulsion co-polymerisation of for example, of one ormore acrylates and (alkyl)acrylates (especially alkylacrylates andalkyl(meth)acrylates); optionally substituted styrenes; methacrylamides;allyl compounds; vinyl ethers; vinyl ketones; vinyl esters; vinylhalides; olefins; unsaturated nitriles and mixtures comprising two ormore of the foregoing, especially latices obtainable by thepolymerisation or emulsion co-polymerisation of the following monomers;methyl methacrlyate, vinyl acetate, methyl acrylate, ethyl acrylate,butyl acrylate, n-hexyl acrylate, n-octyl acrylate, styrene,2-ethylhexyl acrylate, acrylic acid, acrylonitrile, ethylene, vinylacetate, vinyl chloride and ethylene; and especially latices obtainableby the polymerisation or emulsion co-polymerisation of methylmethacrylate with butylacrylate, 2-ethylhexyl acrylate or ethylacrylate.

[0083] In an especially preferred embodiment the latex is stabilised bya water-soluble colloid such as a partially hydrolysedpoly(vinylacetate) or a poly(vinylalcohol), and the latex is one of:

[0084] (i) a latex obtainable by emulsion co-polymerisation of methylmethacrylate with butylacrylate, 2-ethylhexyl acrylate or ethylacrylate;

[0085] (ii) a polyvinylacetate latex; and

[0086] (iii) a latex obtainable by emulsion polymerisation of vinylacetate and ethylene.

[0087] In this especially preferred embodiment the water soluble colloidis preferably a poly(vinylalcohol) such as a Mowiol™ 8-88 and Mowiol™8-18 but is not limited thereto.

[0088] The liquid medium in which the polymer particles are dispersed ispreferably water or a mixture of water and one or more water-miscibleorganic solvent(s). Examples of suitable water-miscible organic solventsare acetic acid, N,N-dimethylformamide, glycols such as ethylene glycol,propylene glycol, dipropylene glycol; methanol, ethanol,dimethylsulphoxide, N-methyl-2-pyrrolidone and lower C₁₋₄-alkylcarbitols such as methyl carbitol. Preferred water-miscible organicsolvents are glycols with 2 to 6 carbon atoms, poly-alkylene glycolswith 4 to 9 carbon atoms or mono C-₁₋₄-alkyl ethers of glycols with 3 to13 carbon atoms. The most preferred water-miscible organic solvent ispropylene glycol.

[0089] The latex may contain other additives, for example viscositycontrol agents, anti-foam additives, pH modifiers, traces of theinitiators and monomers used in the preparation of the latex, colorantsand fillers such as clays, calcium carbonate and calcium sulphates.

[0090] The polymeric biguanide and the isothiazolinone may be added tothe latex sequentially in any order, or simultaneously, to give aconcentration in the latex which is effective to control or eliminatethe growth of micro-organisms in the latex. The amount of polymericbiguanide and isothiazolinone of Formula (1) added to the latex will bedependent upon the nature of the latex, the conditions under which itwill be stored and the particular isothiazolinone and polymericbiguanide selected.

[0091] Preferably sufficient polymeric biguanide is added to the latexto give a concentration therein of from 10 to 1000 ppm by weight of thepolymeric biguanide relative to the total weight of the latex.

[0092] When an isothiazolinone in which Y and Z in Formula (1) are H,halogen or C₁₋₄-alkyl is employed, it is preferred that sufficientisothiazolinone is added to the latex to give a concentration therein offrom 0.5 to 100 ppm, more preferably from 1 to 50 ppm and especiallyfrom 5 to 25 ppm by weight relative to the total weight of the latex.

[0093] When an isothiazolinone in which Y and Z in Formula (1) togetherwith the carbon atoms to which they are attached form an optionallysubstituted 5 or 6 membered ring, especially a benzene ring, isemployed, it is preferred that sufficient isothiazolinone is added tothe latex to give a concentration therein of from 1 to 500 ppm, morepreferably from 5 to 200 ppm by weight relative to the total weight ofthe latex.

[0094] When the polymeric biguanide and isothiazolinone are added to thelatex simultaneously it is preferred that they are added in the form ofa composition comprising the isothiazolinone, the polymeric biguanideand optionally a medium. The medium, when present, is preferably aliquid medium, more preferably water, a mixture of water and one or moreorganic solvents or an organic solvent. Examples of organic solventsthat may be employed include include C₁₋₆-alkanols (especiallyC₁₋₄-alkanols), for example methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol andcyclohexanol; linear amides, preferably dimethylformamide ordimethylacetamide; alkanolamides, for example lactamide,lactamidopropyltrimethylammonium chloride, acetamide andacetamidomonoethanolamine; ketones and ketone-alcohols, preferablyacetone, methyl ether ketone, cyclohexanone and diacetone alcohol;water-miscible ethers, preferably tetrahydrofuran and dioxane; diols,preferably diols having from 2 to 12 carbon atoms, for examplepentane-1,5-diol, ethylene glycol, propylene glycol, 1,3-butyleneglycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo-and poly-alkyleneglycols, preferably diethylene glycol, triethyleneglycol, polyethylene glycol, dipropylene glycol, tripropylene glycol andpolypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol;mono-C₁₋₄-alkyl ethers of diols, preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially 2-methoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol,2-[2-(2-methoxyethoxy)ethoxy]ethanol,2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol, propyleneglycol butyl ether and1-propoxy-2-propanol. It is especially preferred that the medium iswater or a mixture of water and one or more water-miscible organicsolvents. Examples of suitable water-miscible organic solvents areacetic acid, N,N-dimethylformamide, glycols such as ethylene glycol,propylene glycol, dipropylene glycol; methanol, ethanol,dimethylsulphoxide, N-methyl-2-pyrrolidone and lower C₁₋₄-alkylcarbitols such as methyl carbitol. Preferred water-miscible organicsolvents are glycols with 2 to 6 carbon atoms, poly-alkylene glycolsWith 4 to 9 carbon atoms or mono C₁₋₄-alkyl ethers of glycols with 3 to13 carbon atoms. The most preferred water-miscible organic solvent ispropylene glycol. The polymeric biguanide and isothiazolinone may bedissolved in the medium to provide a solution therein. Alternatively oneor both may be present in the medium as an emulsion or dispersion

[0095] Latices treated withg a polymeric biguanide and anisothiazolinone of Formula (1) according to the present method exhibitlong term stability against spoilage by micro-organisms such as fungi,algae, yeasts and especially bacteria.

[0096] According to a further aspect of the present invention there isprovided a composition comprising a latex, a polymeric biguanide and anisothiazolinone of the Formula (1). The preferred polymeric biguanideand isothiazolinone are as hereinbefore described with reference to thefirst aspect of the invention.

[0097] In a preferred embodiment the composition comprises a steric orcationic stabilised acrylic latex; a linear polymeric biguanide which isa mixture of polymer chains in which the individual polymer chains,excluding the terminating groups,. are of the Formula (7) or a saltthereof as hereinbefore described; and a benzisothiazolinone derivativeof the hereinbefore described Formula (2) or a salt or complex thereof.

[0098] We have found that the combination of the polymeric biguanide andisothiazolinone used in the present method exhibits a synergistic effectagainst the micro-organisms commonly found in latices, especiallyagainst fungi such as Aspergillus Niger, yeasts such as Candida albicansand bacteria, especially gram-negative bacteria such as Pseudomonasaeruginosa. Compositions comprising the polymeric biguanide andisothiazolinone used in the method according to the present inventionexhibit a sum of the Fractional Inhibitory Concentration (hereinafterFIC) for each component which is below 1.

[0099] Preferably, the sum of the FIC values is not greater than 0.8,more preferably not greater than 0.7 and especially not greater than0.5. The FIC is the ratio of the amount of each component in thecomposition relative to its Minimum Inhibitory Concentration (MIC) whenused alone. Thus, when the sum of the FIC values is one, the twocomponents exhibit a mere additive effect. When the sum of the FICvalues is below one, the mixture is synergistic. When the sum of the FICvalues is between one and two the two components are considered to beindependent. When the sum of the FIC values is greater than two, themixture is antagonistic. The FIC values are preferably determined byconstructing an isobologram wherein each component in a matrix array isvaried stepwise from a concentration in excess of the MIC down to zeroppm. The isobologram therefore allows the smallest value of the sum ofthe FIC's for each component in the composition to be determined andhence the optimal concentration for each component in the composition.

[0100] Certain compositions used in the method according to the presentinvention are novel.

[0101] According to a further aspect of the present invention there isprovided an anti-microbial composition comprising:

[0102] (i) a linear polymeric biguanide which is a mixture of polymerchains in which the individual polymer chains, excluding the terminatinggroups, are of the Formula (7) or a salt thereof as hereinbeforedescribed; and

[0103] (ii) a benzisothiazolinone derivative of the hereinbeforedescribed Formula (2) or a salt or complex thereof as hereinbeforedescribed.

[0104] Preferred benzisothiazolinone derivatives of Formula (2) are ashereinbefore described with reference to the first aspect of theinvention. It is especially preferred that component (ii) is1,2-benzisothiazolinone.

[0105] The weight ratio of the linear polymeric biguanide:benzisothiazolinone in the anti-microbial composition may vary over widelimits for example from 99:1 to 1:99, more preferably from 10:1 to 1:10.It is especially preferred that the weight ratio of component (i) andcomponent (ii) is close to the lowest sum of the FIC values for each ofthe components as determined from an isobologram as hereinbeforedescribed. It is especially preferred that the weight ratio of thelinear polymeric biguanide benzisothiazolinone in the anti-microbialcomposition is from 4:1 to 1:4.

[0106] As hereinbefore described the anti-microbial compositionsaccording to this aspect of the invention are useful for inhibiting thegrowth of microorganisms in latices. The anti-microbial compositions arealso useful for inhibiting the growth of microorganisms in or on a widerange of other media, especially industrial media. Examples ofindustrial media include cooling water liquors, paper mill liquors,metal working fluids, geological drilling lubricants, polymer emulsions,surface coating compositions (especially varnishes and lacquers) andsolid materials, especially wood, plastics materials and leather. Theamount of the anti-microbial composition according to this aspect of theinvention required to protect such media will be dependant upon themedium to be protected and the conditions to which it will be exposed.Appropriate concentrations of the anti-microbial composition can bereadily determined by those skilled in the art by simple experimentaltrials.

[0107] The anti-microbial composition may be added to the mediumdirectly, however, for ease of handling and dosing, it is generallyconvenient to formulate the anti-microbial composition as a formulationcomprising an anti-microbial composition according to the presentinvention and a carrier.

[0108] The carrier may be a solid but is preferably a liquid and theformulation is preferably a solution, suspension or emulsion of theanti-microbial composition in the liquid.

[0109] The carrier is generally selected so that the anti-microbialcomposition is compatible with the medium to be protected. Thus, forexample, if the medium to be protected is a solvent-based paint, lacqueror varnish the carrier is preferably a solvent, especially a non-polarsolvent such as white spirits (HSCN number 27100021). If the medium tobe protected is a plastics material, the carrier is preferably aplasticiser typically used in the fabrication of plastic articles suchas dioctylphthalate or epoxidised soya bean oil. If the medium to beprotected is an aqueous medium, the carrier is preferably water or awater-miscible organic solvent or mixture thereof. Examples of suitablewater-miscible organic solvents are acetic acid, N,N-dimethylformamide,glycols such as ethylene glycol, propylene glycol, dipropylene glycol;methanol, ethanol, dimethylsulphoxide, N-methyl-2-pyrrolidone and lowerC₁₋₄-alkyl carbitols such as methyl carbitol. Preferred water-miscibleorganic solvents are glycols with 2 to 6 carbon atoms, poly-alkyleneglycols with 4 to 9 carbon atoms or mono C₁₋₄-alkyl ethers of glycolswith 3 to 13 carbon atoms. The most preferred water-miscible organicsolvent is propylene glycol.

[0110] If the formulation is in the form of a suspension or emulsion, itpreferably also contains a surface active agent to produce a stabledispersion or to maintain the non-continuous phase uniformly distributedthroughout the continuous phase. Any surface active agent which does notadversely affect the biocidal activity of the compounds comprising theanti-microbial composition may be used. Preferred surface active agentsare the preferred non-ionic or cationic surfactants and/or dispersantsas hereinbefore described in relation to the first aspect of theinvention, for example alkylene oxide adducts of fatty alcohols, alkylphenols and amines such as ethylene diamine.

[0111] The invention is further illustrated by the following examples inwhich all parts are by weight unless otherwise stated.

EXAMPLE 1 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) and 1.2-Benzisothiazolin-3-one (BIT) Against Pseudomonasaeruginosa.

[0112] Bacteria

[0113]Pseudomonas aeruginosa NCIB 10421

[0114] Method

[0115] Maintenance of Stock Cultures

[0116] Bacteria were maintained on nutrient agar and fungi on malt agaror a spore suspension in physiological saline (0.85% w/v NaCl).

[0117] Calculation of Minimum Inhibitory Concentrations AgainstMono-Cultures

[0118] Bacteria were grown to stationary phase (18h) in nutrient broth(approximately 10⁹ organisms per ml). A 0.1% (v/v) inoculum was used toseed fresh medium and 100 μl of the inoculum was then added to each wellof a microtitre plate, except for the first well which contained 200 μl.

[0119] Using doubling dilutions, the concentration of the compoundsunder investigation were varied in each well along the ordinate axis.The presence or absence of growth was recorded by visual inspectionafter 24 hours incubation at 37° C.

[0120] Calculation of Anti-microbial Activity Against Mono-Cultures

[0121] Microtitre plates were used for this assay. A simple matrix wasconstructed with varied concentrations of the two compounds from 2 × MIC(minimum inhibitory concentration) down to zero concentration in a 10×10array. As the microtitre plate has only 96 wells, the combinations ofthe two compounds that made up the extreme concentrations (highest andlowest) were omitted. Solutions were made up in broth at two times thefinal concentrations after pre-dissolving the compounds in distilledwater.

[0122] The mixture (100 μl) was added to the plate so that the totalvolume in each well was 200 μl. Nutrient broth was used forPs.aeruginosa . Plates were incubated for 16-24 hours at 37°. Thepresence or absence of growth was determined by visual inspection.

[0123] Results TABLE 1 Antimicrobial Activity of Compounds UnderInvestigation Table 1 COMPOUND MIC (ppm) against Ps. aeruginosa BIT 32Vantocil ®™ IB 32

[0124] Calculation of Synergy Against Mono-Cultures

[0125] The Minimum Inhibitory Concentration (MIC) is the lowestconcentration of biocide which showed growth inhibition when used alone.For the purpose of Fractional Inhibitory Concentration (FIC)calculations, if a single biocide did not control growth, the MIC wastaken as the highest concentration used. Fractional InhibitoryConcentrations are the concentration of biocide which controlled growthin the mixture divided by the MIC of that biocide. FIC values for bothcompounds in the mixture were calculated and the results are shown inTable 2. The sum of these two figures gives an indication of the actionof the two biocides. A value less than one indicates a synergisticeffect, if the total is unity or greater the action is additive and ifthe value is greater than two the biocides are antagonistic. If a graphwith the axes representing the biocide Fractional InhibitoryConcentrations for the two biocides on linear scales is constructed,when the combination is additive the isobole ( i.e. the line joining thepoints that represent all combinations with the same effect includingthe equally effective concentrations of the biocides used alone) isstraight, synergistic combinations give concave isoboles andantagonistic combinations give convex isoboles. TABLE 2 FractionalInhibitory Concentrations for BIT and Vantocil ® IB (PHMB) against Ps.aeruginosa Table 2 COMPOUND FIC VALUES Vantocil ® IB 1 0.43 0.29 0.140.14 0.14 0.14 0.00 BIT 0 0.14 0.29 0.43 0.57 0.71 0.86 1.00 Total 10.57 0.58 0.56 0.71 0.85 1.00 1.00

[0126]

[0127] Vantocil®™ IB—is a 20% solution of PHMB hydrochloride availablefrom Avecia Limited.

[0128] BIT—is 1,2-benzisothiazolin-3-one available from Avecia Limitedas PROXEL®™ GXL.

EXAMPLE 2 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) and 2n-Butyl-1,2-benzisothiazolin-3-one (BBIT) AgainstPseudomonas aeruginosa

[0129] Bacteria

[0130]Pseudomonas aeruginosa NCIB 10421

[0131] Method

[0132] Maintenance of Stock Cultures

[0133] Bacteria were maintained on nutrient agar and fungi on malt agaror a spore suspension in physiological saline (0.85% w/v NaCl).

[0134] Calculation of Minimum Inhibitory Concentrations AgainstMonocultures

[0135] Bacteria were grown to stationary phase (18h) in nutrient broth(approximately 10⁹ organisms per ml). A 0.1% (v/v) inoculum was used toseed fresh medium and 100 μl of the inoculum was then added to each wellof a microtitre plate, except for the first well which contained 200 μl.

[0136] Using doubling dilutions, the concentration of the compoundsunder investigation were varied in each well along the ordinate axis.The presence or absence of growth was recorded by visual inspectionafter 24 hours incubation at 37° C.

[0137] Calculation of Anti-Microbial Activity Against Monocultures

[0138] Microtitre plates were used for this assay. A simple matrix wasconstructed with varied concentrations of the two compounds from 2 × MIC(minimum inhibitory concentration) down to zero concentration in a 10×10array. As the microtitre plate has only 96 wells, the combinations ofthe two compounds that made up the extreme concentrations (highest andlowest) were omitted. Solutions were made up in broth at two times thefinal concentrations after pre-dissolving the compounds in distilledwater.

[0139] Each mixture (100 μl) was added to the plate so that the totalvolume in each well was 200 μl. Nutrient broth was used for Ps.aeruginosa. Plates were incubated for 16-24 hours at 37° C. The presenceor absence of growth was determined by visual inspection.

[0140] Results TABLE 3 Antimicrobial Activity of Compounds UnderInvestigation Table 3 COMPOUND MIC (ppm) against Ps. aeruginosa ButylBIT 125 Vantocil ®™ IB 16

[0141] Calculation of Synergy Against Monocultures

[0142] The Minimum Inhibitory Concentration (MIC) is the lowestconcentration of biocide which showed growth inhibition when used alone.For the purpose of Fractional Inhibitory Concentration (FIC)calculations, if a single biocide did not control growth, the MIC wastaken as the highest concentration used. Fractional InhibitoryConcentrations are the concentration of biocide which controlled growthin the mixture divided by the MIC of that biocide. FIC values for bothcompounds in the mixture were calculated and the results are shown inTable 4. The sum of these two figures gives an indication of the actionof the two biocides. A value less than one indicates a synergisticeffect, if the total is unity or greater the action is additive and ifthe value is greater than two the biocides are antagonistic. If a graphwith the axes representing the biocide Fractional Inhibitory

[0143] Concentrations for the two biocides on linear scales isconstructed, when the combination is additive the isobole ( i.e. theline joining the points that represent all combinations with the sameeffect including the equally effective concentrations of the biocidesused alone) is straight, synergistic combinations give concave isobolesand antagonistic combinations give convex isoboles. TABLE 4 FractionalInhibitory Concentrations for Butyl BIT and Vantocil ® IB (PHMB) againstPs. aeruginosa Table 4 COMPOUND FIC VALUES Butyl BIT 0 0.12 0.24 0.37 1Vantocil ® IB 1 0.37 0.25 0.12 0 Total 1 0.49 0.49 0.49 1

[0144] Isobologram 2: Showing Activity of Mixtures of Butyl BIT andVantocil®™ IB (PHMB) Against Ps. aeruginosa

[0145] Vantoci®™ IB—is a 20% solution of PHMB hydrochloride availablefrom Avecia Limited.

[0146] Butyl BIT—is a 98% solution of 2n-butyl-1,2-benzisothiazolin-3-one (BBIT) available from Avecia Limited asDensil®™ DN.

EXAMPLE 3 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) and N-Butyl Benzisothiazolin-3-one (Butyl BIT) AgainstAspergillus Niger

[0147] Fungus

[0148]Aspergillus Niger IMI 17454

[0149] Method

[0150] Maintenance of Stock Cultures

[0151] The fungus was maintained on malt agar.

[0152] Calculation of Minimum Concentrations (MICs) Against Monocultures

[0153] The MICs were calculated as described previously in examples 1and 2.

[0154] Calculation of Anti-Microbial Activity Against Monocultures

[0155] The anti-microbial activity was calculated as describedpreviously in examples 1 and 2.

[0156] Results TABLE 5 Antimicrobial Activity of Compounds UnderInvestigation COMPOUND MIC (ppm) against Aspergillus Niger Butyl BIT 8Vantocil ®™ IB 16

[0157] Calculation of Synergy Against Monocultures

[0158] The synergy against monocultures was calculated as previouslydescribed in examples 1 and 2. TABLE 6 Fractional InhibitoryConcentrations for Butyl BIT and Vantocil ® IB (PHMB) against A. nigerCOMPOUND FIC Values Butyl BIT 0 0.25 0.50 0.66 1 Vantocil ® IB 1 0.500.33 0.16 0 Total 1 0.75 0.83 0.82 1

[0159] Isobologram 3: Showing Acitivity of Mixtures of n-Butyl BIT andVantocil®™ 10 (PHMB) Against Aspergillus Niger

EXAMPLE 4 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) Hydrochloride and CMIT/MIT in VAE Against Acetobacter

[0160] PHMB—is Polyhexamethylene biguanide (PHMB) hydrochlorideavailable from Avecia Limited as Vantocil®™ IB.

[0161] CMIT/MIT—is a 1.5% solution of a 3:1 mixture of5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-oneavailable from Rohm and Haas as Kathon™ LX1.5.

[0162] VAE—is commercially available vinyl acetate ethylene copolymer.

[0163] Bacteria

[0164] An isolate of Acetobacter.

[0165] Method

[0166] Maintenance of Stock Cultures

[0167] The isolate of Acetobacter was grown on potato-dextrose agar(PDA) plates.

[0168] The following method was repeated for examples 4 to 7 as follows:

[0169] VAE (30 g) was weighed into sterile bottles and dosed with thetwo biocides under investigation. The samples were then inoculated witha suspension of bacteria (5% w/w) prepared from an agar lawn andincubated at 30° C. The bacterial growth was assessed by streaking onplates. (PDA for Acetobacter). The samples were judged to be free fromviable bacteria if the plates were free from bacterial coloniesfollowing incubation at 30° C. for 120 hours. The samples werere-inoculated with fresh bacteria (5% w/w) every seven days.

[0170] Results

[0171] Calculation of Synergy Against Monocultures

[0172] Synergy against monocultures was calculates as previouslydescribed. TABLE 7 Fractional Inhibitory Concentrations for Vantocil ®™IB (PHMB) and CMIT/MIT in VAE Against Acetobacter Table 7 COMPOUND FICValues CMIT/MIT 0 0.33 0.67 1 Vantocil ®™ IB 1 0.5 0.13 0 Total 1 0.850.80 1

[0173] CMIT/MIT—is a 1.5% solution of a 3:1 mixture of5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-oneavailable from Rohm and Haas as Kathon™LX1.5.

[0174] Isobologram 4: Showing Activity of Mixtures of Vantocil®™ IB(PHMB) and CMIT/MIT in VAE Against Acetobacter

EXAMPLE 5 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) Hydrochloride and 2-Methyl-4-isothiazolin-3-one (MIT) in VAE(Vinyl Acetate Ethylene Copolymer (VAE)) Against Acetobacter

[0175] MIT—is 2-methyl-4-isothiazolin-3-one available from Rohm and Haasas Kordek™ 50.

[0176] Method

[0177] Example 5 was repeated in exactly the same way as example 4.

[0178] Results TABLE 8 Fractional Inhibitory Concentrations for MIT andVantocil ®™ IB (PHMB) in VAE Against Acetobacter Table 8 COMPOUND FICValues MIT 0 0.33 0.67 1 Vantocil ®™ IB 1 0.50 0.13 0 Total 1 0.83 0.801

[0179] Isobologram 5: Showing Activity of Mixture of Vantocil®™ IB(PHMB) and MIT in VAE Against Acetobacter

EXAMPLE 6 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) Hydrochloride (Vantocil®™ IB) and 1,2-Benzisothiazolin-3-one(BIT) in VAE Against Acetobacter

[0180] BIT is—1,2-benzisothiazolin-3-one available from Avecia Limitedas PROXEL®™ GXL.

[0181] PHMB—is Polyhexamethylene biguanide (PHMB) hydrochlorideavailable from Avecia Limited as Vantocil®™ IB.

[0182] Method

[0183] Example 6 was repeated in exactly the same way as examples 4 and5.

[0184] Results TABLE 9 Fractional inhibitory concentration for BIT andPHMB (Vantocil ®™ IB) in VAE against Acetobacter Table 9 COMPOUND FICValues BIT 0 0.33 0.67 1 PHMB Vantocil ® ™IB 1 0.50 0.13 0 Total 1 0.830.80 1

[0185] Isobologram 6: Showing Activity of Mixtures of Vantocil®™ IB(PHMB) and BIT in VAE Against Acetobacter

EXAMPLE 7 Investigation of Synergy Between Polyhexamethylene Biguanide(PHMB) Hydrochloride (Vantocil®™ IB) and2N-Butyl-1,2-Benzisothiazolin-3-one (Butyl BIT) in VAE AgainstAcetobacter

[0186] Butyl BIT—is a 98% solution of 2n-butyl-1,2-benzisothiazolin-3-one (BBIT) available from Avecia Limited asDensil®™ DN.

[0187] Vantocil®™ IB—is a 20% solution of polyhexamethylene biguanide(PHMB) hydrochloride available from Avecia Limited.

[0188] Method

[0189] Example 7 was repeated in exactly the same way as examples 4 to6.

[0190] Results TABLE 10 Fractional inhibitory concentrations for PHMB(Vantocil ®™ IB) and Butyl BIT in VAE against Acetobacter Table 10COMPOUND FIC Values Butyl BIT 0 0.20 0.40 1 PHMB (Vantocil ®™ IB) 1 0.670.33 0 Total 1 0.87 0.73 1

[0191] Isobologram 7: Showing Activity of Mixture of Vantocil®™ IB(PHMB) and Butyl BIT in VAE Against Acetobacter

EXAMPLE 8

[0192] Suitable formulations for use in inhibiting the growth ofmicro-organisms is a latex according to the present invention but notlimited thereto were prepared as follows.

EXAMPLE 8a Polyhexamethylene Biguanide (PHMB) (Vantocil®™ IB) and2N-Butyl-1,2-Benzisothiazolin-3-one (BBIT) Formulation

[0193] Order of Components Weight % addition Vantocil ®™ IB is a 20%solution of Polyhexamethylene 84.2 1 biguanide hydrochloride availablefrom Avecia Limited. Makon ™ 8 (Is ethoxylated nonyl phenol, availablefrom Stepan 10.5 2 Company) Densil ®™ DN is a 98% solution of2n-Butyl-1,2- 5.3 3 Benzisothiazolin-3-one available from AveciaLimited. Procedure: Makon ™ 8 was added to Vantocil ®™ IB with stirring.Densil ®™ DN was then added slowly to achieve a clear light brownsolution

EXAMPLE 8b Polyhexamethylene Biguanide (PHMB) (Vantocil®™ IB) and1.2-Benzisothiazolin-3-one (BIT) Formulation

[0194] Order of Components Weight % addition Mixture 1 Cremaphor ™ PS20Ester (Polyoxyethylene Sorbitan 90 1 Monolaurate available from BASFCorporation) Proxel ®™ Press paste (1,2-Benzisothiazolin-3-one available10 2 from Avecia Inc. The components were mixed and then heated withfurther agitation at 50° C. until all of the BIT (Proxel ®™) dissolved.This resulted in a dark amber solution.

[0195] Example 8b continued Order of Components Weight % additionMixture 2 Vantocil ®™ IB (20% solution of Polyhexamethylene biguanide71.1 1 hydrochloride available from Avecia Limited). Mixture 1 28.6 2Surfynol ™ 104 PG (acetylenic diol available from Air Products 0.3 3 andChemicals Inc.) Procedure: Mixture 1 was added to Vantocil ®™ IBstepwise with continued stirring, ensuring that the mixture was clearbefore the addition of another portion. Surfynol ™ 104 PG was alsoadded. The complete addition of mixture 1 resulted in a clear dark brownsolution.

EXAMPLE 8c Polyhexamethylene Biguanide (PHMB) Hydrochloride (Vantocil®™IB) and 2-methyl-4-isothiazolin-3-one (MIT) Formulation

[0196] Order of Components Weight % addition Vantocil ® IB (20% solutionof Polyhexamethylene biguanide 55.56 1 hydrochloride available fromAvecia Limited). Propylene Glycol (Available from Lyondell ChemicalCompany) 33.33 2 Kordek ™ 50C (a 50% composition of MIT available from11.11 3 Rohm & Haas) Procedure: Propylene glycol was added to theVantocil ® IB with stirring. Kordek ™ 50C was then slowly added to themixture with continued stirring which resulted in a clear light tansolution.

EXAMPLE 8d Polyhexamethylene Biguanide (PHMB) Hydrochloride (Vantocil®™IB) and CMIT/MIT Formulation

[0197] Order of Components Weight % addition Vantocil ® IB (20% solutionof Polyhexamethylene biguanide 64.1 1 (PHMB) hydrochloride availablefrom Avecia Limited). Propylene Glycol (available from Lyondell ChemicalCompany) 25.6 2 Kathon ™ WT (8.6% CMIT(5-chloro-2-methyl-4-isothiazolinone- 10.3 3 3-one), 2.6% MIT(2-methyl-4-isothiazolin-3-one) available from Rohm & Haas) Procedure:Propylene glycol was added to Vantocil ® IB with stirring. Kathon ™ WTwas then added slowly to the mixture with further stirring. Thisresulted in the formation of a clear yellow solution

1. A method for inhibiting the growth of micro-organisms in a latexcomprising adding to the latex: (a) a polymeric biguanide; and (b) anisothiazolinone of the Formula (1) or a salt or complex thereof:

wherein: R is H, alkyl, cycloalkyl or aralkyl; and Y and Z eachindependently are H, halogen or C₁₋₄-alkyl or Y and Z together with thecarbon atoms to which they are attached form an optionally substituted 5or 6 membered ring.
 2. A method according to claim 1 wherein: R is H,C₁₋₈-alkyl, C₃₋₅ -cycloalkyl or aralkyl; and Y and Z are H, halogen orC₁₋₄-alkyl.
 3. A method according to claim 1 wherein: R is H, methyl,butyl or octyl; and Y and Z each independently are hydrogen, or togetherform an optionally substituted 6 membered ring.
 4. A method according toclaim 1 wherein the isothiazolinone of Formula (1) is5-chloro-2-methyl-⁴-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one,4,5-dichloro-2-methylisothiazolin-3-one 2-n-octylisothiazolin-3-one,1,2-benzisothiazolin-3-one, 4,5-trimethylene-4-isothiazolin-3-one,2-methyl-4,5-trimethylene-4-isothiazolin-3-one or2-n-butyl-1,2-benzisothiazolin-3-one or a mixture comprising two or moreof the foregoing compounds.
 5. A method according to claim 1 wherein theisothiazolinone of Formula (1) is a benzisothiazolinone of the Formula(2) or a salt or complex thereof:

wherein: R¹ is hydroxy, halogen (especially chlorine), C₁₋₄-alkyl orC₁₋₄-alkoxy; R is as defined in claim 1; and n is from 0to
 4. 6. Amethod according to claim 5 wherein. the benzisothiazolinone is1,2-benzisothiazolin-3-one.
 7. A method according to claim 5 wherein thebenzisothiazolinone is 2-n-butyl-1,2-benzisothiazolin-3-one.
 8. A methodaccording to any one of the preceding claims wherein the polymericbiguanide comprises at least two biguanide units of Formula (3):

linked by a bridging group which contains at least one methylene group.9. A method according to any one of the preceding claims wherein thepolymeric biguanide is a linear polymeric biguanide comprising a mixtureof polymer chains in which the individual polymer chains, excluding theterminating groups, are of the Formula (7) or a salt thereof:

wherein n is from 4 to
 40. 10. A method according to any one of thepreceding claims wherein the latex is a cationic or stericallystabilised latex.
 11. A method according to any one of the precedingclaims wherein the latex is substantially free from anionic compounds.12. A method according to any one of the preceding claims wherein thelatex is stabilised with a partially hydrolysed poly(vinylacetate) or apoly(vinylalcohol).
 13. A method according to any one of the precedingclaims wherein the latex is stabilised by a water-soluble colloid, andthe latex is selected from: (i) a latex obtainable by emulsionco-polymerisation of methyl methacrylate with butyl acrylate,2-ethylhexyl acrylate or ethyl acrylate; (ii) a polyvinylacetate latex;and (iii) a latex obtainable by emulsion polymerisation of vinyl acetateand ethylene.
 14. A method according to any one of the preceding claimswherein the isothiazolinone and polymeric biguanide are added to thelatex in the form of a composition comprising the isothiazolinone, thepolymeric biguanide and optionally a medium.
 15. A compositioncomprising a latex, a polymeric biguanide and an isothiazolinone of theFormula (1) as defined in claim
 1. 16. An anti-microbial compositioncomprising: (i) a linear polymeric biguanide which is a mixture ofpolymer chains in which the individual polymer chains, excluding theterminating groups, are of the Formula (7) or a salt thereof as definedin claim 9; and (ii) a benzisothiazolinone derivative of the Formula (2)or a salt or complex thereof as defined in claim 5.